#include <math.h>

#include <iostream>
#include <opencv2/opencv.hpp>

using namespace cv;

int main(int argc, char** argv) {
  Mat src, dst;
  src = imread("../images/1.jpg");
  if (!src.data) {
    printf("could not load image...\n");
    return -1;
  }
  namedWindow("input image", CV_WINDOW_AUTOSIZE);
  imshow("input image", src);

  /*
  int cols = (src.cols-1) * src.channels();
  int offsetx = src.channels();
  int rows = src.rows;

  dst = Mat::zeros(src.size(), src.type());
  for (int row = 1; row < (rows - 1); row++) {
          const uchar* previous = src.ptr<uchar>(row - 1);
          const uchar* current = src.ptr<uchar>(row);
          const uchar* next = src.ptr<uchar>(row + 1);
          uchar* output = dst.ptr<uchar>(row);
          for (int col = offsetx; col < cols; col++) {
                  output[col] = saturate_cast<uchar>(5 * current[col] -
  (current[col- offsetx] + current[col+ offsetx] + previous[col] + next[col]));
          }
  }
  */
  double t = getTickCount();
  Mat kernel = (Mat_<char>(3, 3) << 0, -1, 0, -1, 5, -1, 0, -1, 0);
  filter2D(src, dst, src.depth(), kernel);
  double timeconsume = (getTickCount() - t) / getTickFrequency();
  printf("tim consume %.2f\n", timeconsume);

  namedWindow("contrast image demo", CV_WINDOW_AUTOSIZE);
  imshow("contrast image demo", dst);

  waitKey(0);
  return 0;
}